There seems to be a fundamental difference between "REPL"s and "REPL but more like a shell" that we continue to run into when discussing REPLs. If you take a look at the blogpost (or the video adamkl posted in this thread), you'll see that the REPL discussed works in a fundamentally different way than what Ruby and Elixir does.

There is some more discussion around this whole REPL vs shell thing here too: https://twitter.com/VictorBjelkholm/status/12660699623613726...

Edit: Funnily I just discovered your blogpost is titled "interactive shell" but your comment talks about REPL ;)